Question

If a is a non - singular matrix of size 3 3, then adj (adj a) is equal to

Answer 1

Answer:

A / |A|

Step-by-step explanation:

Need:

• X ( adj X ) = |X| I

Then...

A ( adj A ) = |A| I  =>  |A| |adj A| = |A|  =>  |adj A| = 1.

Also, putting X = adj A in the above....

( adj A ) ( adj ( adj A ) ) = |adj A| I = I

Multiplying on the left by A, we then get

A ( adj A ) ( adj ( adj A ) ) = A

=> |A| ( adj ( adj A ) ) = A

=> adj ( adj A ) = A / |A|